1. Field of the Invention
This invention relates to pistons for internal combustion engines, and particularly those made of ferrous material.
2. Related Art
Pistons for gasoline engines used in passenger and light and medium duty truck applications are typically made of aluminum. Aluminum is light, relatively easy to cast, and relatively inexpensive to make for large volume usage. Vehicle manufactures arc demanding more power and improved fuel economy out of the same or smaller size engines. Such requirements present a challenge to piston manufactures since there are presently limits on what can be achieved with a standard aluminum piston. For example, the aluminum pistons may not be able to perform adequately under increased temperatures and pressures caused by advanced technologies used to achieve more power and fuel economy. In order to withstand and perform under the increased combustion temperatures and pressures, some piston manufactures have taken to using steel pistons. Such steel pistons oftentimes include one or more closed cooling galleries to retain cooling oil for cooling the upper crown, which is directly exposed to the high temperatures and pressures of the combustion chamber.